Poiseuille, Jean-Louis(-Marie) (1799-1869)

French physiologist who made a key contribution to our knowledge of the circulation of blood in the arteries. He also studied the flow of liquids in artificial capillaries.

Poiseuille was born in Paris and studied at the Ecole Polytechnique. In 1842 he was elected to the Académie de Médicine in Paris.

Poiseuille improved on earlier measurements of blood pressure by using a mercury manometer and filling the connection to the artery with potassium carbonate to prevent coagulation. He used this instrument, known as a hemodynamometer, to show that blood pressure rises during expiration (breathing out) and falls during inspiration (breathing in). He also discovered that the dilation of an artery fell to less than 1/20 of its normal value during a heartbeat.